SYNOPSIS

DESCRIPTION

A device ID consists of two parts:
a major ID, identifying the class of the device,
and a minor ID, identifying a specific instance of a device in that class.
A device ID is represented using the type
dev_t.

Given major and minor device IDs,
makedev()
combines these to produce a device ID, returned as the function result.
This device ID can be given to
mknod(2),
for example.

The
major()
and
minor()
functions perform the converse task: given a device ID,
they return, respectively, the major and minor components.
These macros can be useful to, for example,
decompose the device IDs in the structure returned by
stat(2).

CONFORMING TO

The
makedev()
major()
and
minor()
functions are not specified in POSIX.1,
but are present on many other systems.

NOTES

These interfaces are defined as macros.
Since glibc 2.3.3,
they have been aliases for three GNU-specific functions:
gnu_dev_makedev(3),
gnu_dev_major(3),
and
gnu_dev_minor(3).
The latter names are exported, but the traditional names are more portable.